For us, it was roughly 2 TFs every 25 boss kill, but maybe we're really (un)lucky, hard to say. Need bigger sample pool. Either way, that's way more than I expected, although RNG will still be there for some specific drops.

Needs clarification if this is 10 man or 25 man. Blizzard already said that as an incentive to running 25 man they would see much more frequent TF'd drops than 10 man would. Also even if this was a 10 man run there is such a thing as really, really good RNG.

We got two Thunderfucked items. (That's what we call them since they have been a pain in the dick for our DKP system...) Anyway, we got some intellect legs off the first boss and some agility mail somethingerothers off one of the other bosses. We killed the first three last night, so 2 pieces out of three bosses so far.